11165857921 has 4 divisors (see below), whose sum is σ = 11213780292. Its totient is φ = 11117935552.

The previous prime is 11165857903. The next prime is 11165857931. The reversal of 11165857921 is 12975856111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12975856111 = 23 ⋅564167657.

It can be written as a sum of positive squares in 2 ways, for example, as 2015022321 + 9150835600 = 44889^2 + 95660^2 .

It is a cyclic number.

It is not a de Polignac number, because 11165857921 - 2³¹ = 9018374273 is a prime.

It is a super-2 number, since 2×11165857921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11165857931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23960836 + ... + 23961301.

It is an arithmetic number, because the mean of its divisors is an integer number (2803445073).

Almost surely, 2^11165857921 is an apocalyptic number.

It is an amenable number.

11165857921 is a deficient number, since it is larger than the sum of its proper divisors (47922371).

11165857921 is an equidigital number, since it uses as much as digits as its factorization.

11165857921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47922370.

The product of its digits is 151200, while the sum is 46.

The spelling of 11165857921 in words is "eleven billion, one hundred sixty-five million, eight hundred fifty-seven thousand, nine hundred twenty-one".